Broadband optical coupling using dispersive elements

ABSTRACT

Embodiments include a fiber to photonic chip coupling system including a collimating lens which collimate a light transmitted from a light source and an optical grating including a plurality of grating sections. The system also includes an optical dispersion element which separates the collimated light from the collimating lens into a plurality of light beams and direct each of the plurality of light beams to a respective section of the plurality of grating sections. Each light beam in the plurality of light beams is diffracted from the optical dispersion element at a different wavelength a light beam of the plurality of light beams is directed to a respective section of the plurality of grating sections at a respective incidence angle based on the wavelength of the light beam of the plurality of light beams to provide optimum grating coupling.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.16/864,104 filed Apr. 30, 2020 and issued as U.S. Pat. No. 11,366,270B2. The aforementioned related patent application is herein incorporatedby reference in its entirety.

TECHNICAL FIELD

Embodiments presented in this disclosure generally relate to couplinglight from optical fibers with photonic devices. More specifically,embodiments disclosed herein provide for efficient broadband couplingfrom optical fibers to photonic devices, such as silicon photonic chips,using dispersion elements and optical grating to provide for peakcoupling efficiency of the light to the photonic chip.

BACKGROUND

Fiber optics are used to quickly and efficiently transmit informationusing light. One of the limiting factors in the operation of the fiberoptics is the coupling of the light transmitted through the opticalfibers to optoelectronic and photonic devices. One method to providecoupling between optical fibers and various devices is to use opticalgrating, such as silicon grating. However, optical coupling using anoptical grating has limited light spectrum bandwidth, which in turnlimits the application of optical grating to specific types of opticalcommunication systems.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above-recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this disclosure and are therefore not to beconsidered limiting of its scope, for the disclosure may admit to otherequally effective embodiments.

FIG. 1A illustrates a fiber to photonic chip coupling system with adispersive element, according to one embodiment.

FIG. 1B illustrates a packaging configuration of fiber to photonic chipcoupling system with a dispersive element, according to one embodiment.

FIG. 1C illustrates light coupling mechanism of photonic grating couplerin a fiber to photonic chip coupling system, according to oneembodiment.

FIG. 1D illustrates example coupling efficiency spectrums for a fiber tophotonic chip coupling system without a dispersive element and a fiberto photonic chip coupling system with a dispersive element, according toexample embodiments.

FIG. 2 illustrates an optical free space wavelength separator withtransmissive gratings as a dispersive element, according to oneembodiment.

FIG. 3 illustrates an optical free space wavelength separator with anoptical Gradient-index lens with integrated transmissive gratings as adispersive element, according to one embodiment.

FIG. 4 illustrates a method to assemble a fiber to photonic chipcoupling system with a dispersive element, according to embodimentsdescribed herein.

FIG. 5 is a block diagram of a system for assembling a fiber to photonicchip coupling system with a dispersive element, according to one or moreembodiments.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements disclosed in oneembodiment may be beneficially utilized on other embodiments withoutspecific recitation.

DESCRIPTION OF EXAMPLE EMBODIMENTS

Overview

One general aspect includes a fiber to photonic chip coupling systemwith a dispersive element. The optical coupling system also includes acollimating lens configured to collimate a light transmitted from alight source. The optical coupling system also includes an opticalgrating which may include a plurality of grating sections and an opticaldispersion element configured to separate the collimated light from thecollimating lens into a plurality of light beams. The optical dispersionelement also directs each of the plurality of light beams to arespective section of the plurality of grating sections at respectiveoptimum incidence angle, where each light beam in the plurality of lightbeams is diffracted from the optical dispersion element at a differentwavelength, and where a light beam of the plurality of light beams isdirected to a respective section of the plurality of grating sections atrespective optimum incidence angle based on the wavelength of the lightbeam of the plurality of light beams.

One example embodiment includes an optical dispersion element configuredto separate a collimated light into a plurality of light beams anddirect each of the plurality of light beams to a respective section ofan optical coupling grating at respective optimum incidence angle, whereeach light beam in the plurality of light beams is diffracted from theoptical dispersion element at a different wavelength, and wherein alight beam of the plurality of light beams is directed to a respectivesection of a plurality of grating sections on an associated opticalgrating at respective optimum incidence angle based on the wavelength ofthe light beam of the plurality of light beams.

A system of one or more computers can be configured to performparticular operations or actions by virtue of having software, firmware,hardware, or a combination of them installed on the system that inoperation causes or cause the system to perform the actions. One or morecomputer programs can be configured to perform particular operations oractions by virtue of including instructions that, when executed by dataprocessing apparatus, cause the apparatus to perform the actions. Onegeneral aspect includes a method. The method includes receiving awavelength spectrum for a light from an optical source, determining awavelength for each of a plurality of light beams of the light separatedby an optical dispersion element, determining a plurality of incidenceangles for each determined wavelength or wavelength band based on theoptical grating coupler, and determining a position of the opticaldispersion element in the optical coupling system according to theplurality of incidence angles. Other embodiments of this aspect includecorresponding computer systems, apparatus, and computer programsrecorded on one or more computer storage devices, each configured toperform the actions of the methods.

Example Embodiments

Fiber optic communication systems are increasingly a ubiquitous part ofmodern communication and data transmission. As more and more servicesutilize fiber optic communications, efficiencies in the fiber opticsystems need to be maximized in order to streamline production of thefiber optic systems and avoid unnecessary or expensive components in thefiber optic communication systems.

One example limiting factor in the operation of the fiber opticcommunication systems is the efficient coupling of light from a fiber toa photonic chip without increasing the costs of the coupling components.Several methods exist including various types of optical coupling;however, coupling using optical grating couplers has emerged as acommonly used and low-cost way to couple light from fibers to photonicchips. Grating couplers provide efficiency as they can be placedanywhere on a photonic chip as opposed to other types of couplers whichmay require a device edge or other structure to provide coupling.Grating couplers also require less precise alignment between a fiber andthe photonic chip, thus reducing some active alignment processesrequired in other edge types.

However, optical grating has limited bandwidth response when compared toother more expensive coupling methods such as edge-coupling. Thislimited bandwidth is due to the fact that each wavelength has adifferent spectrum response to the grating. These limitations of theoptical grating, in turn, limit the application of the lower costoptical grating couplings to specific types of optical communicationsystems.

The systems, couplers, and dispersion elements described herein providea fiber to photonic chip coupling system including an optical dispersionelement which directs light beams from a fiber optic light source to arespective grating section of an optical grating connected to a photonicchip with a responsive optimum incidence angle based on the wavelength.The light beams are directed to a grating section with an optimumincidence angle which provides a peak or optimum coupling efficiency forthe wavelength of the light beam. This enables the grating to provide anefficient and broadband spectrum response to the optical fiber.

FIG. 1A illustrates a fiber to photonic chip coupling system with adispersive element, according to one embodiment. The fiber to photonicchip coupling system, system 100, includes an optical source, lightsource 105 (e.g., a light source such as a fiber optical cable, multiplefiber optic cables, etc.), an optical free space wavelength separator110, which includes a collimated lens and a dispersive element describedbelow, and a photonic chip 150. The photonic chip 150 is any type ofphotonic and/or optoelectronic device that may interact withoptical/light sources, such as optical fibers. For example, the photonicchip 150 may be a photonic chip among a plurality of photonic chipsaffixed to a substrate (e.g., a wafer, etc.). The photonic chip 150includes a waveguide 155, which may include a plurality of variouswaveguides providing an optical path from a grating coupler, opticalgrating 130, to the various optical and electronic elements of thephotonic chip 150.

In an example where the optical free space wavelength separator 110 isnot used in the coupling scheme from the light source 105 to thephotonic chip 150 (example not shown), the light source 105 is coupleddirectly to the optical grating 130. A light from the light source 105then couples to the waveguides 155 of the photonic chip 150 at a reducedor narrow band spectrum due to power coupling inefficiencies wherevarious wavelengths of the light from the light source 105 havenon-optimal incidence angles. The non-optimal incidence angles causeinefficient coupling of the light such that only a limited band of thelight from the light source 105 is able to efficiently and reliablycouple to the waveguides 155.

One example coupling efficiency is shown in as shown in FIG. 1D, whichillustrates coupling efficiency bandwidth for coupled lights. As shown,a plot 171 illustrates an example coupling efficiency for a directcoupling between the light source 105 and the optical grating 130. Inthis example, the coupling efficiency is greatest for a specificwavelength (e.g., approximately 1310 nm where the grating's 1 dBbandwidth is approximately 35 nanometers (e.g., approximately 1295-1330nm based on the incidence angle). In contrast, a plot 172 illustrates anexample coupling efficiency for a coupling between the light source-105and the optical grating 130 using a coupling the optical free spacewavelength separator as described herein. As shown, the 1 dB bandwidthfor the plot 172 is above 100 nm (i.e. almost tripling the couplingspectrum bandwidth of the direct coupling of the plot 171).

Turning back to FIG. 1A, the optical free space wavelength separator 110includes a collimating lens 115 and a dispersion element 120. Thecollimating lens 115 receives an un-collimated light 106 from the lightsource 105 and outputs the collimated light 116 which includes variousrays of collimated light. The collimated light 116 is directed to thedispersion element 120. In some examples, the collimating lens 115 is acomponent of or integrated with the light source 105. For example, thelight source 105 is a fiber optic cable with a lens attached to an endor terminus of the fiber as discussed in relation to FIG. 2 . Thecollimating lens 115 may be collocated with the dispersion element 120as discussed in relation to FIG. 3 .

The dispersion element 120 separates the collimated light 116 into aplurality of light beams such as light beams 121-123. While shown asthree light beams in FIG. 1 for ease of illustration, the collimatedlight 116 may be separated into many light beams, where each light beamincludes light with a respective wavelength or band of wavelengths i.e.,wavelength bands. For example, the light beam 121 may include light witha wavelength of 1271 nm or a band of light where the wavelength of theband of light ranges from 1264.5 nm to 1277.5 nm, among other examples.

The various wavelengths of the light beams 121-123 are directed torespective sections of the optical grating 130, including sections131-133. The sections correspond to an incidence angle between the lightbeams 121-123 and a top surface 130 a of the optical grating 130 thatprovides peak coupling efficiency for the wavelength of the respectivelight beam. For example, the light beam 121 is directed from thedispersion element 120 to the section 131, such that the light beam 121interacts with the optical grating 130 at a first incidence angle (θ₁)141. The light beam 122 interacts with the section 132 at a secondincidence angle (θ₂) 142. The light beam 123 interacts with the section133 at a third incidence angle (θ₃) 143. The various pairings of thelight beams and incidence angles provides for greater power coupling ofthe light beams to the waveguide 155 via the optical grating 130.Incidence angles which provide peak or optimal coupling efficiency arediscussed in more detail in relation to FIG. 1C and FIG. 4 .

In some examples, the dispersion element 120 is a reflective diffractivegrating (e.g., a near-infrared blazed reflective grating) whichseparates the collimated light 116 into the light beams 121-123 anddirects/reflects the separated or diffracted light beams 121-123 towardsthe optical grating 130 as shown in FIG. 1A.

In some examples, the components of the optical free space wavelengthseparator 110 are positioned/disposed on and supported by variousmechanical packaging structures as shown in FIG. 1B, which illustrates apackaging configuration of fiber to photonic chip coupling system with adispersive element. For example, the collimating lens 115 is disposedbetween the structure 161 and the structure 163. The dispersion element120 is disposed on the structure 163 and the structure 162. The photonicchip 150 may also be associated with a cladding 151 disposed on andaround the grating 130, as shown in in FIG. 1B.

Furthermore, the position of dispersion element 120 within the opticalfree space wavelength separator 110 is at an angle 170 with respect tothe optical grating 130. In some examples, The position of thedispersion element 120 can also be adjusted to alter the angle 170 andan angle 175 and in turn the incidence angles 141-143 described in FIG.1A to provide a peak coupling efficiency for the light.

In some examples, the peak coupling efficiency between the light beams121-123 and the optical grating 130 depends on and can be determinedusing the wavelength of the individual light beams 121-123 shown in FIG.1A, the incidence angle to the top surface 130 a, the properties of theoptical grating 130, and the dispersion element 120. FIG. 1C illustratesa light coupling mechanism of photonic grating coupler in a fiber tophotonic chip coupling system, such as the system 100. For gratingcouplers, such as the grating 130, the wavevector of the incident light(e.g., a light beam 125) needs to meet certain conditions in relation tothe wavevector of the light coupled in the grating 130, i.e. coupledlight 135, as well as the wavevector of grating 130 itself as describedin Equations 1-5 below.

A horizontal component of the wave vector (ki₁₂₅) of the incident lightis a function of the wave vector equation, the incidence angle (θ₁₄₅)between the light beam 125 and the grating 130, and an index of anycladding, such as cladding 151 above the grating 130 (nc₁₅₁), and thewavelength of the incident light (λ₁₂₅) as shown in Equation 1 below. Insome examples, the cladding 151 is an oxide cladding deposited on thegrating 130 between the dispersion element 120 and the grating 130.

A wave vector of the grating 130 (K₁₃₀) is a function of the period ofthe grating coupler (Λ₁₃₀) as shown in Equation 2. The wave vector(kcoupled₁₃₁) of the incident light once coupled to the grating 130,i.e. coupled light 135, is a function of λ₁₂₅ and an effective index ofthe grating 130 (neff₁₃₀). In order to conserve the momentum inhorizontal direction, kcoupled₁₃₁ is equal to the summation of ki₁₂₅ andK₁₃₀ as shown in Equation 4. The various values from equations 1-3 canbe used to solve for an optimum θ₁₄₅ to provide peak coupling efficiencyfor the incidence light at a certain wavelength as shown in Equation 5and discussed in more detail in relation to FIG. 4 .ki ₁₂₅=(2π/λ₁₂₅)*nc ₁₅₁*sin θ₁₄₅  Equation (1):K ₁₃₀=2π/Λ₁₃₀  Equation (2):kcoupled₁₃₅=2π/λ₁₂₅ *neff₁₃₀  Equation (3):ki ₁₂₅ +K ₁₃₀ =kcoupled₁₃₅  Equation (4):2π/λ₁₂₅ *nc ₁₅₁*sin θ₁₄₅+2π/λ₁₃₀=2π/λ*neff₁₃₀  Equation (5):

FIG. 2 illustrates an optical free space wavelength separator usingtransmissive gratings as a dispersive element such as an optical freespace wavelength separator 210, according to one embodiment. The opticalfree space wavelength separator 210 may be used in place of the opticalfree space wavelength separator 110 in the system 100 described in FIG.1A. The optical free space wavelength separator 210 includes acollimating lens 215 and a transmissive dispersion element 220. Thecollimating lens 215 receives an un-collimated light 206 from an opticalsource, such as light source 105, and outputs the collimated light 216.The collimated light 216 is directed to the transmissive dispersionelement 220. In some examples, the collimating lens 215 is a componentof or integrated with the light source 105. For example, the lightsource 105 is a fiber optic cable with a lens attached to an end orterminus of the fiber. The collimating lens 215 may also be collocatedwith the dispersion element 220 as discussed in relation to FIG. 3 .

The transmissive dispersion element 220 separates the collimated light216 into a plurality of light beams such as light beams 221, 222, 223.While shown as three light beams in FIG. 2 for ease of illustration, thecollimated light 216 may be separated into many light beams, where eachlight beam includes light with a respective wavelength or band ofwavelengths. For example, the light beam 221 may include light with awavelength of 1271 nm or a band of light where the wavelength of theband of light ranges from 1264.5 nm to 1277.5 nm, among other examples.

The various wavelengths of the light beams 221, 222, 223 are directed tosections of the optical grating 230 in a manner similar to sections131-132 of the grating 130 in FIG. 1A. The sections correspond to anincidence angle between the light beams 221, 222, 223 and a top surfaceof the optical grating 230 that provides peak coupling efficiency forthe wavelength of the respective light beam.

FIG. 3 illustrates an optical free space wavelength separator usingoptical GRIN (Gradient-index) lens integrated with transmissive gratingsas an optical free space wavelength separator 310, according to oneembodiment. The optical free space wavelength separator 310 may be usedin place of the optical free space wavelength separator 110 in thesystem 100, as describe in FIG. 1A. The optical free space wavelengthseparator 310 includes gradient-index (GRIN) lens 315 and a transmissivediffractive grating 320 formed on a polished end-face of the GRIN lens315. The GRIN lens 315 receives an un-collimated light 306 from anoptical source, such as light source 105, and collimates the light intothe collimated light 316. The collimated light 316 is directed to thetransmissive diffractive grating 320.

The transmissive diffractive grating 320 separates the collimated light316 into a plurality of light beams such as light beams 321, 322, 323.While shown as three light beams in FIG. 3 for ease of illustration, thecollimated light 316 may be separated into many light beams, where eachlight beam includes light with a respective wavelength or band ofwavelengths.

The various wavelengths of the light beams 321, 322, 323 are directed tosections of the optical grating 330 in a manner similar to sections131-132 of the grating 130 in FIG. 1A. The sections correspond to anincidence angle between the light beams 321, 322, 323 and a top surfaceof the optical grating 330 that provides peak coupling efficiency forthe wavelength of the respective light beam.

FIG. 4 illustrates a method to assemble a fiber to photonic chipcoupling system with a dispersive element, according to embodimentsdescribed herein. Method 400 begins at block 402 where a fiber tophotonic chip optical coupler module, such as optical coupler module 520discussed in relation to FIG. 5 , receives a wavelength spectrum for alight from an optical source. In some examples, the information isreceived from a user or system for a specific light source output froman optical fiber (e.g., a light source with a spectrum of 1260-1340 nm).For example, the system 500 receives information regarding thewavelength spectrum for a light such as the un-collimated light 106,206, and 306 discussed in relation to FIGS. 1A, 2, and 3 . For example,the system 500 receives data indicating the wavelength spectrum for theun-collimated light 106 is 1260-1340 nm.

At block 404, the optical coupler module 520 determines a wavelength foreach of a plurality of light beams of the light separated by an opticaldispersion element. For example, given grating coupler properties for aspecific optical dispersion element such as the dispersion element 120,transmissive dispersion element 220, and/or the transmissive diffractivegrating 320 the optical coupler module 520 determines how many lightbeams and the wavelength of the light beams that will be produced by theoptical dispersion element. For example, as shown in FIG. 1A thedispersion element 120 produces 3 light beams 121-123.

At block 406, the optical coupler module 520 determines a plurality ofincidence angles for each determined wavelength or wavelength band basedon grating coupler properties. For example, given a wavelength for alight beam of the plurality of light beams, the optical coupler module520 uses the equations 1-5 discussed in relation to FIG. 1C and givengrating coupler properties to determine an optimal incidence angle forthe wavelength of each light beam including factoring in any additionalinformation for the optical coupler. For example, a light beam with awavelength of 1280 nm will have an optimal incidence angle such as θ₁₄₅at 21.9 degrees based on a grating coupler design.

In some examples, the optical dispersion element is designed to separatethe light beam into a plurality of different wavelengths withcorresponding angles to interact with the optical grating. For example,the optical dispersion element is designed such that the diffractionangles for each determined wavelength from the dispersion element areequal to the incidence angles for each determined wavelength to theoptical grating.

Once the designed angles and wavelengths are known a position of thedispersive element can be determined to ensure the light beams interactwith the optical grating at optimum incidence angles.

In some examples, as discussed in relation to FIGS. 1B, 2, and 3 , theoptical dispersion element includes a reflective diffractive grating ora transmissive diffractive grating. The positioning of the opticaldispersion element depends on the type of the grating. For example, whenas shown in FIG. 1B, the optical coupler module 520 determines aposition of the dispersion element 120 in the structures 162 and 163 inorder to provide the determined incidence angles for the wavelengths ofthe light beams. For example, the module 520 determines the angle 170such that when the dispersion element 120 is fixed in place and thecollimated light 116 interacts with the dispersion element 120, thelight beams 121-123 interact with the grating 130 according to thedetermined incidence angles determined in block 406. In another example,such as the transmissive dispersion element 220 and/or the GRIN lens315, the position of the transmissive dispersion element 220 and thetransmissive diffractive grating 320 on the GRIN lens 315 is determinedin order to provide their respective light beams the determinedincidence angles to the optical gratings 230 and 330 respectively.

At block 408, the optical coupler module 520 positions the opticaldispersion element in the optical system according to the determinedposition. For example, the optical coupler module 520 using thealignment system 540 and attachment system 545 positions and verifiesthat the optical dispersion element is positioned with the assembly toensure the light beams interact with the optical grating at optimumincidence angles.

FIG. 5 is a block diagram of a system 500 for constructing an opticalapparatus including an optical coupler module as described herein,according to one or more embodiments. Features of the system 500 may beused in conjunction with other embodiments, such as the various opticalcoupling system, fiber optic communication systems, and dispersionelements, which are discussed above in relation to FIGS. 1A-4 .

The system 500 comprises a controller 505 comprising one or morecomputer processors 510 and a memory 515. The one or more computerprocessors 510 represent any number of processing elements that each caninclude any number of processing cores. Some non-limiting examples ofthe one or more computer processors 510 include a microprocessor, adigital signal processor (DSP), an application-specific integrated chip(ASIC), and a field programmable gate array (FPGA), or combinationsthereof. The memory 515 may comprise volatile memory elements (such asrandom access memory), non-volatile memory elements (such assolid-state, magnetic, optical, or Flash-based storage), andcombinations thereof. Moreover, the memory 515 may be distributed acrossdifferent mediums (e.g., network storage or external hard drives).

The memory 515 may comprise a plurality of “modules” for performingvarious functions described herein. In one embodiment, each moduleincludes program code that is executable by one or more of the computerprocessors 510. However, other embodiments may include modules that arepartially or fully implemented in hardware (i.e., circuitry) or firmwareof the controller 505. As shown, the memory 515 comprises an opticalcoupler module 520 configured to control various stages of manufacturing(or assembling) an optical coupling system as described in relation toFIGS. 1A-4 . The optical coupler module 520 is configured to communicatecontrol signals to one or more systems via a network 525. The network525 may include one or more networks of various types, including apersonal area network (PAN), a local area or local access network (LAN),a general wide area network (WAN), and/or a public network (e.g., theInternet).

As shown, the system 500 comprises an actuation system 530, an alignmentsystem 540, and an attachment system 545, each of which iscommunicatively coupled with the controller 505 via the network 525.Based on control signals received from the controller 505, one or moreof these systems may be configured to manipulate one or more components555, such as semiconductor substrates (e.g., photonic chip 150) and/oroptical components (the dispersion element 120, and related componentssuch as the collimating lenses) when constructing the optical apparatus.

In some embodiments, the actuation system 530 is configured to alter anorientation of the components 555 (e.g., translation and/or rotation)between different stages of processing, maintain an orientation of thecomponents 555 during the processing, and so forth. For example, theactuation system 530 may comprise one or more robotic arms and/orgripping systems.

As part of constructing the optical apparatus, a plurality of opticalfibers, and/or other optical and/or electronic components may be placedon the components 555. In some embodiments, the alignment system 540 isconfigured to perform an optical alignment of the collating lens, thedispersion elements and the optical gratings. For example, the alignmentsystem 540 may comprise an active alignment system configured to provideoptical signals to the optical fibers and/or lenses to generate anoptical signal.

In some embodiments, the alignment system 540 is used to optically alignthe plurality of optical fibers and the optical coupling system afterattachment to the components 555. For example, the alignment system 540may manipulate the components 555 to align the dispersion element andgratings and the plurality of optical fibers with respective waveguidesformed in a photonic substrate. In other embodiments, the alignmentsystem 540 may operate in conjunction with the actuation system 530 tomanipulate the components 555 and/or the semiconductor substrate.

In some embodiments, the attachment system 545 is configured to attachthe components 555 with one or more of: other substrates, components555, the optical coupling system, the plurality of optical fibers, andother optical and/or electronic components according to any suitabletechniques. In some embodiments, the attachment system 545 may be usedin multiple attachment stages. For example, the attachment system 545may be configured to apply an epoxy between the optical fibers, thestructures 161-162, and a first one of the components 555, to apply anepoxy between the first one and a second one of the components 555, toapply an epoxy between the first one of the components 555 and asemiconductor substrate, and so forth. The attachment system 545 mayfurther be configured to cure the epoxy, e.g., by applying anultraviolet (UV) light.

The controller 505 may be implemented in any suitable form. In someembodiments, the controller 505 comprises a singular computing deviceproviding centralized control of the construction process. In otherembodiments, the controller 505 represents multiple, communicativelycoupled computing devices, which may or may not have centralizedcontrol. For example, some or all of the actuation system 530, thealignment system 540, and the attachment system 545 may comprise localcontrollers that are in communication with the controller 505 via thenetwork 525. In an alternate embodiment, the operation of the actuationsystem 530, the alignment system 540, and the attachment system 545 maybe achieved independently of centralized control.

Further, while the system 500 is described primarily in terms ofmanipulating the components 555, the various systems described hereinmay interact with other components as part of constructing the opticalcoupling system. For example, the actuation system 530 may be configuredto manipulate the plurality of optical fibers, and other electricaland/or optical components.

To further improve optical coupling, vision-assisted alignment or activealignment may be performed in a limited number of axes. Sinceinterlocking the alignment features or other features of the substrateis effective to provide at least a coarse alignment of the opticalfibers with the waveguides of the substrate, the vision-assistedalignment or the active alignment may be used to provide a fineralignment while adding minimal process time. Use of these simple andinexpensive mechanical features to “pre-align” the optical couplingsystem to the photonic chip can reduce or eliminate the cost ofautomation (e.g., precision placement and peak searching algorithms),ultimately reducing the overall cost of alignment.

In the preceding, reference is made to embodiments presented in thisdisclosure. However, the scope of the present disclosure is not limitedto specific described embodiments. Instead, any combination of thedescribed features and elements, whether related to differentembodiments or not, is contemplated to implement and practicecontemplated embodiments. Furthermore, although embodiments disclosedherein may achieve advantages over other possible solutions or over theprior art, whether or not a particular advantage is achieved by a givenembodiment is not limiting of the scope of the present disclosure. Thus,the preceding aspects, features, embodiments and advantages are merelyillustrative and are not considered elements or limitations of theappended claims except where explicitly recited in a claim(s).

As will be appreciated by one skilled in the art, the embodimentsdisclosed herein may be embodied as a system, method or computer programproduct. Accordingly, aspects may take the form of an entirely hardwareembodiment, an entirely software embodiment (including firmware,resident software, micro-code, etc.) or an embodiment combining softwareand hardware aspects that may all generally be referred to herein as a“circuit,” “module” or “system.” Furthermore, aspects may take the formof a computer program product embodied in one or more computer readablemedium(s) having computer readable program code embodied thereon.

Any combination of one or more computer readable medium(s) may beutilized. The computer readable medium may be a computer readable signalmedium or a computer readable storage medium. A computer readablestorage medium may be, for example, but not limited to, an electronic,magnetic, optical, electromagnetic, infrared, or semiconductor system,apparatus, or device, or any suitable combination of the foregoing. Morespecific examples (a non-exhaustive list) of the computer readablestorage medium would include the following: an electrical connectionhaving one or more wires, a portable computer diskette, a hard disk, arandom access memory (RAM), a read-only memory (ROM), an erasableprogrammable read-only memory (EPROM or Flash memory), an optical fiber,a portable compact disc read-only memory (CD-ROM), an optical storagedevice, a magnetic storage device, or any suitable combination of theforegoing. In the context of this document, a computer readable storagemedium is any tangible medium that can contain, or store a program foruse by or in connection with an instruction execution system, apparatusor device.

A computer readable signal medium may include a propagated data signalwith computer readable program code embodied therein, for example, inbaseband or as part of a carrier wave. Such a propagated signal may takeany of a variety of forms, including, but not limited to,electro-magnetic, optical, or any suitable combination thereof. Acomputer readable signal medium may be any computer readable medium thatis not a computer readable storage medium and that can communicate,propagate, or transport a program for use by or in connection with aninstruction execution system, apparatus, or device.

Program code embodied on a computer readable medium may be transmittedusing any appropriate medium, including but not limited to wireless,wireline, optical fiber cable, RF, etc., or any suitable combination ofthe foregoing.

Computer program code for carrying out operations for aspects of thepresent disclosure may be written in any combination of one or moreprogramming languages, including an object oriented programming languagesuch as Java, Smalltalk, C++ or the like and conventional proceduralprogramming languages, such as the “C” programming language or similarprogramming languages. The program code may execute entirely on theuser's computer, partly on the user's computer, as a stand-alonesoftware package, partly on the user's computer and partly on a remotecomputer or entirely on the remote computer or server. In the latterscenario, the remote computer may be connected to the user's computerthrough any type of network, including a local area network (LAN) or awide area network (WAN), or the connection may be made to an externalcomputer (for example, through the Internet using an Internet ServiceProvider).

Aspects of the present disclosure are described below with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems) and computer program products according to embodimentspresented in this disclosure. It will be understood that each block ofthe flowchart illustrations and/or block diagrams, and combinations ofblocks in the flowchart illustrations and/or block diagrams, can beimplemented by computer program instructions. These computer programinstructions may be provided to a processor of a general purposecomputer, special purpose computer, or other programmable dataprocessing apparatus to produce a machine, such that the instructions,which execute via the processor of the computer or other programmabledata processing apparatus, create means for implementing thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

These computer program instructions may also be stored in a computerreadable medium that can direct a computer, other programmable dataprocessing apparatus, or other devices to function in a particularmanner, such that the instructions stored in the computer readablemedium produce an article of manufacture including instructions whichimplement the function/act specified in the flowchart and/or blockdiagram block or blocks.

The computer program instructions may also be loaded onto a computer,other programmable data processing apparatus, or other devices to causea series of operational steps to be performed on the computer, otherprogrammable apparatus or other devices to produce a computerimplemented process such that the instructions which execute on thecomputer or other programmable apparatus provide processes forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality and operation of possible implementations ofsystems, methods and computer program products according to variousembodiments. In this regard, each block in the flowchart or blockdiagrams may represent a module, segment or portion of code, whichcomprises one or more executable instructions for implementing thespecified logical function(s). It should also be noted that, in somealternative implementations, the functions noted in the block may occurout of the order noted in the figures. For example, two blocks shown insuccession may, in fact, be executed substantially concurrently, or theblocks may sometimes be executed in the reverse order, depending uponthe functionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts, or combinations of special purpose hardware andcomputer instructions.

In view of the foregoing, the scope of the present disclosure isdetermined by the claims that follow.

In the preceding, reference is made to embodiments presented in thisdisclosure. However, the scope of the present disclosure is not limitedto specific described embodiments. Instead, any combination of thedescribed features and elements, whether related to differentembodiments or not, is contemplated to implement and practicecontemplated embodiments. Furthermore, although embodiments disclosedherein may achieve advantages over other possible solutions or over theprior art, whether or not a particular advantage is achieved by a givenembodiment is not limiting of the scope of the present disclosure. Thus,the preceding aspects, features, embodiments and advantages are merelyillustrative and are not considered elements or limitations of theappended claims except where explicitly recited in a claim(s).

In view of the foregoing, the scope of the present disclosure isdetermined by the claims that follow.

We claim:
 1. A method comprising: receiving a wavelength spectrum for alight from an optical source; determining a plurality of incidenceangles for each determined wavelength band of a plurality of wavelengthbands in the wavelength spectrum from an optical dispersion elementbased on grating coupler properties; determining a position for theoptical dispersion element in an optical coupling system according tothe plurality of incidence angles, wherein the optical dispersionelement comprises a lens comprising a transmissive diffractive gratingformed on a polished end-face of the lens; and positioning the opticaldispersion element in the optical coupling system according to theposition.
 2. The method of claim 1, wherein the position of the opticaldispersion element directs a plurality of light beams from the opticaldispersion element to respective sections of a plurality of gratingsections on an optical grating based on the wavelength of the light beamof the plurality of light beams.
 3. The method of claim 2, wherein afirst beam of the plurality of light beams comprises a first wavelength,wherein positioning the optical dispersion element further comprises:directing the first beam to a first section of the plurality of gratingsections to interact with the first section at a first incidence angle,wherein the first incidence angle provides a first peak couplingefficiency for the first wavelength.
 4. The method of claim 3, wherein asecond beam of the plurality of light beams comprises a secondwavelength, wherein positioning the optical dispersion element furthercomprises: directing the second beam to a second section of theplurality of grating sections to interact with the second section at asecond incidence angle, wherein the second incidence angle provides asecond peak coupling efficiency for the second wavelength.
 5. The methodof claim 1, wherein the optical dispersion element comprises one of areflective diffractive grating and a transmissive diffractive grating.6. The method of claim 1, wherein the optical dispersion elementcomprises a gradient-index (GRIN) lens, wherein the transmissivediffractive grating is formed on a polished end-face of the GRIN lens.7. The method of claim 1, wherein the optical source comprises anoptical source connected with an optical fiber transmitting anun-collimated light to a coupling system.